/*
** $Id: lstate.h $
** Global State
** See Copyright Notice in lua.h
*/

#ifndef lstate_h
#define lstate_h

#include "lua.h"

#include "lobject.h"
#include "ltm.h"
#include "lzio.h"


/*
** Some notes about garbage-collected objects: All objects in Lua must
** be kept somehow accessible until being freed, so all objects always
** belong to one (and only one) of these lists, using field 'next' of
** the 'CommonHeader' for the link:
**
** 'allgc': all objects not marked for finalization;
** 'finobj': all objects marked for finalization;
** 'tobefnz': all objects ready to be finalized;
** 'fixedgc': all objects that are not to be collected (currently
** only small strings, such as reserved words).
**
** For the generational collector, some of these lists have marks for
** generations. Each mark points to the first element in the list for
** that particular generation; that generation goes until the next mark.
**
** 'allgc' -> 'survival': new objects;
** 'survival' -> 'old': objects that survived one collection;
** 'old1' -> 'reallyold': objects that became old in last collection;
** 'reallyold' -> NULL: objects old for more than one cycle.
**
** 'finobj' -> 'finobjsur': new objects marked for finalization;
** 'finobjsur' -> 'finobjold1': survived   """";
** 'finobjold1' -> 'finobjrold': just old  """";
** 'finobjrold' -> NULL: really old       """".
**
** All lists can contain elements older than their main ages, due
** to 'luaC_checkfinalizer' and 'udata2finalize', which move
** objects between the normal lists and the "marked for finalization"
** lists. Moreover, barriers can age young objects in young lists as
** OLD0, which then become OLD1. However, a list never contains
** elements younger than their main ages.
**
** The generational collector also uses a pointer 'firstold1', which
** points to the first OLD1 object in the list. It is used to optimize
** 'markold'. (Potentially OLD1 objects can be anywhere between 'allgc'
** and 'reallyold', but often the list has no OLD1 objects or they are
** after 'old1'.) Note the difference between it and 'old1':
** 'firstold1': no OLD1 objects before this point; there can be all
**   ages after it.
** 'old1': no objects younger than OLD1 after this point.
*/

/*
** Moreover, there is another set of lists that control gray objects.
** These lists are linked by fields 'gclist'. (All objects that
** can become gray have such a field. The field is not the same
** in all objects, but it always has this name.)  Any gray object
** must belong to one of these lists, and all objects in these lists
** must be gray (with two exceptions explained below):
**
** 'gray': regular gray objects, still waiting to be visited.
** 'grayagain': objects that must be revisited at the atomic phase.
**   That includes
**   - black objects got in a write barrier;
**   - all kinds of weak tables during propagation phase;
**   - all threads.
** 'weak': tables with weak values to be cleared;
** 'ephemeron': ephemeron tables with white->white entries;
** 'allweak': tables with weak keys and/or weak values to be cleared.
**
** The exceptions to that "gray rule" are:
** - TOUCHED2 objects in generational mode stay in a gray list (because
** they must be visited again at the end of the cycle), but they are
** marked black because assignments to them must activate barriers (to
** move them back to TOUCHED1).
** - Open upvales are kept gray to avoid barriers, but they stay out
** of gray lists. (They don't even have a 'gclist' field.)
*/



/*
** About 'nCcalls':  This count has two parts: the lower 16 bits counts
** the number of recursive invocations in the C stack; the higher
** 16 bits counts the number of non-yieldable calls in the stack.
** (They are together so that we can change and save both with one
** instruction.)
*/


/* true if this thread does not have non-yieldable calls in the stack */
#define yieldable(L)  (((L)->nCcalls & 0xffff0000) == 0)

/* real number of C calls */
#define getCcalls(L) ((L)->nCcalls & 0xffff)


/* Increment the number of non-yieldable calls */
#define incnny(L) ((L)->nCcalls += 0x10000)

/* Decrement the number of non-yieldable calls */
#define decnny(L) ((L)->nCcalls -= 0x10000)

/* Non-yieldable call increment */
#define nyci (0x10000 | 1)




struct lua_longjmp;  /* defined in ldo.c */


/*
** Atomic type (relative to signals) to better ensure that 'lua_sethook'
** is thread safe
*/
#if !defined(l_signalT)
#include <signal.h>
#define l_signalT sig_atomic_t
#endif


/*
** Extra stack space to handle TM calls and some other extras. This
** space is not included in 'stack_last'. It is used only to avoid stack
** checks, either because the element will be promptly popped or because
** there will be a stack check soon after the push. Function frames
** never use this extra space, so it does not need to be kept clean.
*/
#define EXTRA_STACK   5


#define BASIC_STACK_SIZE        (2*LUA_MINSTACK)

#define stacksize(th) cast_int((th)->stack_last - (th)->stack)


/* kinds of Garbage Collection */
#define KGC_INC  0 /* incremental gc */
#define KGC_GEN  1 /* generational gc */


typedef struct stringtable {
    TString **hash;
    int nuse;  /* number of elements */
    int size;
} stringtable;


/*
** Information about a call.
*/
typedef struct CallInfo {
    StkId func;  /* function index in the stack */
    StkId top;  /* top for this function */
    struct CallInfo *previous, *next;  /* dynamic call link */
    union {
        struct {  /* only for Lua functions */
            const Instruction *savedpc;
            volatile l_signalT trap;
            int nextraargs;  /* # of extra arguments in vararg functions */
        } l;
        struct {  /* only for C functions */
            lua_KFunction k;  /* continuation in case of yields */
            ptrdiff_t old_errfunc;
            lua_KContext ctx;  /* context info. in case of yields */
        } c;
    } u;
    union {
        int funcidx;  /* called-function index */
        int nyield;  /* number of values yielded */
        struct {  /* info about transferred values (for call/return hooks) */
            unsigned short ftransfer;  /* offset of first value transferred */
            unsigned short ntransfer;  /* number of values transferred */
        } transferinfo;
    } u2;
    short nresults;  /* expected number of results from this function */
    unsigned short callstatus;
} CallInfo;


/*
** Bits in CallInfo status
*/
#define CIST_OAH (1<<0) /* original value of 'allowhook' */
#define CIST_C  (1<<1) /* call is running a C function */
#define CIST_FRESH (1<<2)  /* call is on a fresh "luaV_execute" frame */
#define CIST_HOOKED (1<<3) /* call is running a debug hook */
#define CIST_YPCALL (1<<4) /* call is a yieldable protected call */
#define CIST_TAIL (1<<5) /* call was tail called */
#define CIST_HOOKYIELD (1<<6) /* last hook called yielded */
#define CIST_FIN (1<<7)  /* call is running a finalizer */
#define CIST_TRAN (1<<8) /* 'ci' has transfer information */
#if defined(LUA_COMPAT_LT_LE)
#define CIST_LEQ (1<<9)  /* using __lt for __le */
#endif

/* active function is a Lua function */
#define isLua(ci) (!((ci)->callstatus & CIST_C))

/* call is running Lua code (not a hook) */
#define isLuacode(ci) (!((ci)->callstatus & (CIST_C | CIST_HOOKED)))

/* assume that CIST_OAH has offset 0 and that 'v' is strictly 0/1 */
#define setoah(st,v) ((st) = ((st) & ~CIST_OAH) | (v))
#define getoah(st) ((st) & CIST_OAH)


/*
** 'global state', shared by all threads of this state
*/
typedef struct global_State {
    lua_Alloc frealloc;  /* function to reallocate memory */
    void *ud;         /* auxiliary data to 'frealloc' */
    l_mem totalbytes;  /* number of bytes currently allocated - GCdebt */
    l_mem GCdebt;  /* bytes allocated not yet compensated by the collector */
    lu_mem GCestimate;  /* an estimate of the non-garbage memory in use */
    lu_mem lastatomic;  /* see function 'genstep' in file 'lgc.c' */
    stringtable strt;  /* hash table for strings */
    TValue l_registry;
    TValue nilvalue;  /* a nil value */
    unsigned int seed;  /* randomized seed for hashes */
    lu_byte currentwhite;
    lu_byte gcstate;  /* state of garbage collector */
    lu_byte gckind;  /* kind of GC running */
    lu_byte genminormul;  /* control for minor generational collections */
    lu_byte genmajormul;  /* control for major generational collections */
    lu_byte gcrunning;  /* true if GC is running */
    lu_byte gcemergency;  /* true if this is an emergency collection */
    lu_byte gcpause;  /* size of pause between successive GCs */
    lu_byte gcstepmul;  /* GC "speed" */
    lu_byte gcstepsize;  /* (log2 of) GC granularity */
    GCObject *allgc;  /* list of all collectable objects */
    GCObject **sweepgc;  /* current position of sweep in list */
    GCObject *finobj;  /* list of collectable objects with finalizers */
    GCObject *gray;  /* list of gray objects */
    GCObject *grayagain;  /* list of objects to be traversed atomically */
    GCObject *weak;  /* list of tables with weak values */
    GCObject *ephemeron;  /* list of ephemeron tables (weak keys) */
    GCObject *allweak;  /* list of all-weak tables */
    GCObject *tobefnz;  /* list of userdata to be GC */
    GCObject *fixedgc;  /* list of objects not to be collected */
    /* fields for generational collector */
    GCObject *survival;  /* start of objects that survived one GC cycle */
    GCObject *old1;  /* start of old1 objects */
    GCObject *reallyold;  /* objects more than one cycle old ("really old") */
    GCObject *firstold1;  /* first OLD1 object in the list (if any) */
    GCObject *finobjsur;  /* list of survival objects with finalizers */
    GCObject *finobjold1;  /* list of old1 objects with finalizers */
    GCObject *finobjrold;  /* list of really old objects with finalizers */
    struct lua_State *twups;  /* list of threads with open upvalues */
    lua_CFunction panic;  /* to be called in unprotected errors */
    struct lua_State *mainthread;
    TString *memerrmsg;  /* message for memory-allocation errors */
    TString *tmname[TM_N];  /* array with tag-method names */
    struct Table *mt[LUA_NUMTAGS];  /* metatables for basic types */
    TString *strcache[STRCACHE_N][STRCACHE_M];  /* cache for strings in API */
    lua_WarnFunction warnf;  /* warning function */
    void *ud_warn;         /* auxiliary data to 'warnf' */
} global_State;


/*
** 'per thread' state
*/
struct lua_State {
    CommonHeader;
    lu_byte status;
    lu_byte allowhook;
    unsigned short nci;  /* number of items in 'ci' list */
    StkId top;  /* first free slot in the stack */
    global_State *l_G;
    CallInfo *ci;  /* call info for current function */
    StkId stack_last;  /* end of stack (last element + 1) */
    StkId stack;  /* stack base */
    UpVal *openupval;  /* list of open upvalues in this stack */
    GCObject *gclist;
    struct lua_State *twups;  /* list of threads with open upvalues */
    struct lua_longjmp *errorJmp;  /* current error recover point */
    CallInfo base_ci;  /* CallInfo for first level (C calling Lua) */
    volatile lua_Hook hook;
    ptrdiff_t errfunc;  /* current error handling function (stack index) */
    l_uint32 nCcalls;  /* number of nested (non-yieldable | C)  calls */
    int oldpc;  /* last pc traced */
    int basehookcount;
    int hookcount;
    volatile l_signalT hookmask;
};


#define G(L) (L->l_G)


/*
** Union of all collectable objects (only for conversions)
** ISO C99, 6.5.2.3 p.5:
** "if a union contains several structures that share a common initial
** sequence [...], and if the union object currently contains one
** of these structures, it is permitted to inspect the common initial
** part of any of them anywhere that a declaration of the complete type
** of the union is visible."
*/
union GCUnion {
    GCObject gc;  /* common header */
    struct TString ts;
    struct Udata u;
    union Closure cl;
    struct Table h;
    struct Proto p;
    struct lua_State th;  /* thread */
    struct UpVal upv;
};


/*
** ISO C99, 6.7.2.1 p.14:
** "A pointer to a union object, suitably converted, points to each of
** its members [...], and vice versa."
*/
#define cast_u(o) cast(union GCUnion *, (o))

/* macros to convert a GCObject into a specific value */
#define gco2ts(o)  \
 check_exp(novariant((o)->tt) == LUA_TSTRING, &((cast_u(o))->ts))
#define gco2u(o)  check_exp((o)->tt == LUA_VUSERDATA, &((cast_u(o))->u))
#define gco2lcl(o)  check_exp((o)->tt == LUA_VLCL, &((cast_u(o))->cl.l))
#define gco2ccl(o)  check_exp((o)->tt == LUA_VCCL, &((cast_u(o))->cl.c))
#define gco2cl(o)  \
 check_exp(novariant((o)->tt) == LUA_TFUNCTION, &((cast_u(o))->cl))
#define gco2t(o)  check_exp((o)->tt == LUA_VTABLE, &((cast_u(o))->h))
#define gco2p(o)  check_exp((o)->tt == LUA_VPROTO, &((cast_u(o))->p))
#define gco2th(o)  check_exp((o)->tt == LUA_VTHREAD, &((cast_u(o))->th))
#define gco2upv(o) check_exp((o)->tt == LUA_VUPVAL, &((cast_u(o))->upv))


/*
** macro to convert a Lua object into a GCObject
** (The access to 'tt' tries to ensure that 'v' is actually a Lua object.)
*/
#define obj2gco(v) check_exp((v)->tt >= LUA_TSTRING, &(cast_u(v)->gc))


/* actual number of total bytes allocated */
#define gettotalbytes(g) cast(lu_mem, (g)->totalbytes + (g)->GCdebt)

LUAI_FUNC void luaE_setdebt (global_State *g, l_mem debt);
LUAI_FUNC void luaE_freethread (lua_State *L, lua_State *L1);
LUAI_FUNC CallInfo *luaE_extendCI (lua_State *L);
LUAI_FUNC void luaE_freeCI (lua_State *L);
LUAI_FUNC void luaE_shrinkCI (lua_State *L);
LUAI_FUNC void luaE_checkcstack (lua_State *L);
LUAI_FUNC void luaE_incCstack (lua_State *L);
LUAI_FUNC void luaE_warning (lua_State *L, const char *msg, int tocont);
LUAI_FUNC void luaE_warnerror (lua_State *L, const char *where);


#endif

